Research!

Inspiration just struck for an alternate history story which will require research. Two items in my random idea file collided. Mmm, research! Good idea file. Extra biscuit!
I’m really excited by this idea, but, once again, it’s a situation without a plot. That happens to me a lot; I get a situation, or a character, or even characters in a situation, but there’s no plot. Here, Plot!
Here’s my sleepy question: Is it fantasy because of spoiler, or is it science fiction because it’s alternate history?
P.S. Oh my darling Critters! I missed you so much!